Liquid crystal display (LCD) device is a currently widely used display device and generally includes a display panel and a backlight for bearing the display panel and providing backlight for the display panel. In the existing LCD device, a wavelength of light emitted by the backlight basically has been determined when produced by backlight manufacturers. However, with the increased requirements on the display effect of the LCD device, an improvement in the color gamut of the LCD device has become the trends of future technical development.